The present invention relates generally to explosive warheads and, more particularly, to methods and apparatus for embedding an initiator within a main explosive charge and the warheads formed thereby.
As illustrated in FIG. 1, it is known to provide a warhead 10 including a fixed initiator 12. More particularly, the initiator 12 usually includes an initiator charge 14 coupled to a safe/arm device (not shown) through a precision initiating coupling (PIC) 16. The initiator charge 14 is typically in a fixed position by being rigidly coupled to the warhead case 20. As is known, the initiator charge 14 is configured to bridge a gap 22 and detonate a main explosive charge 24. The gap 22 between the initiator charge 14 and the main explosive charge 24 may degrade the performance of the warhead 10.
Another known warhead 30 is shown in FIG. 2 as including an initiator 32 which is configured to move longitudinally within the case 20. More particularly, the initiator housing 34 is rigidly coupled to the warhead case 20 and defines a chamber or passageway 36 in which the initiator 32 floats. As such, the initiator 32 may move up and down within its housing 34 to maintain contact with the main explosive charge 24. In certain instances, springs 38 may be used to exert a downward force against the initiator 32, thereby facilitating contact between the initiator and the explosive charge 24. As noted above, maintaining contact between the initiator 32 and the main explosive charge 24 may be important, particularly when using a weaker initiator 32, in order to provide satisfactory performance of the main explosive charge 24 or when greater initiation precision is desired.
With reference now to FIG. 3, in order to facilitate contact between the initiator 32 and the main explosive charge 24, it is known to use an end former 38 for casting a precision upper surface 40 on the main explosive charge 24. Spruel holes 42 may be utilized to either cast liquid explosive 24 through the end former 38 or permit the discharge of excess liquid explosive 24 therethrough.
There remains a need for a warhead with increased performance through consistently reliable and precise initiation of the main explosive charge and, more particularly, by allowing the initiator to maintain full and continuous contact with the main explosive charge as the relative position between the case and upper surface of the main explosive charge changes. There is also a need to simplify and economize production of warheads by eliminating the need to end form a precision upper surface on the main explosive charge. There is a further need to permit initiator removal and replacement while maintaining the main explosive charge within the case. There is also a need to improve the safety of warheads by protecting the relatively sensitive initiator from the case of the warhead.
According to an illustrative embodiment of the present disclosure, an explosive warhead includes a case defining a longitudinal axis, and a main explosive charge received within the case. An explosive initiator includes an embedded portion received within the main explosive charge. A coupler is positioned intermediate the main explosive charge and the embedded portion of the initiator, and releasably couples the initiator to the main explosive charge. The explosive initiator maintains continuous contact with the main explosive charge by moving longitudinally with the main explosive charge during thermal expansion and contraction. Illustratively, the coupler includes a plurality of threads formed within the main explosive charge, and a plurality of mating threads supported by the embedded portion of the initiator.
According to another illustrative embodiment of the present disclosure, an explosive warhead includes a case defining a longitudinal axis, a main explosive charge received within the case, and an explosive initiator which includes an embedded portion received within the main explosive charge. A longitudinally extending spruel hole is formed within the initiator and receives a portion of the main explosive charge.
According to a further illustrative embodiment of the present disclosure, an explosive warhead includes a case, a main explosive charge received within the case, and an explosive initiator including an embedded portion received within the main explosive charge. A ullage is disposed intermediate the explosive initiator and the case, wherein the explosive initiator maintains continuous contact with the main explosive charge by moving within the ullage during thermal expansion and contraction of the main explosive charge.
According to yet another illustrative embodiment of the present disclosure, a method of forming an explosive warhead includes the steps of providing a case, coupling an initiator to a placement fixture, and positioning the placement fixture such that the initiator is suspended within a liquid explosive received within the case. The method further includes the step of curing the liquid explosive to a hardened condition such that the initiator is at least partially embedded within and supported by the explosive.
According to a further illustrative embodiment of the present disclosure, a method of forming an explosive warhead includes the steps of providing a case, coupling an initiator to a placement fixture, and positioning the placement fixture such that the initiator is suspended within the case. The method further includes the steps of casting a liquid explosive within the case, such that at least a portion of the initiator is received within the liquid explosive when suspended within the case by the placement fixture, and curing the liquid explosive to a hardened condition, such that the initiator is at least partially embedded within and supported by the explosive.
According to a further illustrative embodiment of the present disclosure, a method of forming an explosive warhead includes the steps of providing a case, providing an initiator including threads, and coupling the initiator to a placement fixture. The method further includes the steps of coupling the placement fixture to the case such that the initiator is suspended within the case, and casting a liquid explosive within the case, such that at least a portion of the initiator is received within the liquid explosive when suspended within the case by the placement fixture. The method further includes the steps of heating the liquid explosive such that the explosive hardens, the initiator is at least partially embedded within and supported by the explosive, and mating threads are formed within the explosive and cooperate with the threads of the initiator. The method further includes the steps of uncoupling the initiator from the placement fixture after the explosive hardens, cooling the explosive after uncoupling the initiator, such that the initiator moves with the explosive in response to thermal contraction, and uncoupling the placement fixture from the case.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.